US4106425A - Marine propulsion unit with protected screw - Google Patents

Marine propulsion unit with protected screw Download PDF

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Publication number
US4106425A
US4106425A US05/793,305 US79330577A US4106425A US 4106425 A US4106425 A US 4106425A US 79330577 A US79330577 A US 79330577A US 4106425 A US4106425 A US 4106425A
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US
United States
Prior art keywords
section
screw
unit
passage
set forth
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US05/793,305
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English (en)
Inventor
Ludwig Gruber
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JOHN GmbH
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JOHN GmbH
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Publication date
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H20/00—Outboard propulsion units, e.g. outboard motors or Z-drives; Arrangements thereof on vessels
    • B63H20/007—Trolling propulsion units
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H5/00—Arrangements on vessels of propulsion elements directly acting on water
    • B63H5/07—Arrangements on vessels of propulsion elements directly acting on water of propellers
    • B63H5/14—Arrangements on vessels of propulsion elements directly acting on water of propellers characterised by being mounted in non-rotating ducts or rings, e.g. adjustable for steering purpose
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B61/00—Adaptations of engines for driving vehicles or for driving propellers; Combinations of engines with gearing
    • F02B61/04—Adaptations of engines for driving vehicles or for driving propellers; Combinations of engines with gearing for driving propellers
    • F02B61/045—Adaptations of engines for driving vehicles or for driving propellers; Combinations of engines with gearing for driving propellers for marine engines

Definitions

  • This invention relates to marine propulsion units, and particularly to a propulsion unit having a screw which is rotated rapidly enough to injure a swimmer in adjacent water.
  • the invention in one of its more specific aspects, provides a propulsion unit which includes an elongated casing formed with a passage therethrough which is of substantially circular cross section transverse to a longitudinal axis.
  • a driven propelling screw is mounted in an axially central portion of the passage for rotation in a plane perpendicular to the axis, and protective devices are arranged in each of the two axially terminal portions of the passage for preventing insertion of a limb of a human adult or child to a depth sufficient to reach the screw without substantially impeding axial flow of water through the two terminal portions.
  • FIG. 1 shows a vessel equipped with the marine propulsion unit of the invention in a perspective view
  • FIG. 2 illustrates the inverted drive motor and associated elements of the propulsion unit in side elevation
  • FIG. 3 shows the propulsion unit in side elevation, its casing being partly broken away to reveal internal structure, and the figure being drawn to scale;
  • FIG. 4 is a rear elevation of the device of FIG. 3 on the same scale as FIG. 3;
  • FIG. 5 illustrates a test stand carrying the propulsion unit without its casing, the view being in side elevation.
  • an inflatable rubber dinghy 5 whose propulsion unit includes an electric motor 2 mounted on the hull of the dinghy 5 by means of a bracket 4 rotatably receiving a supporting rod 3.
  • the lower end of the rod is attached to the motor 2, the upper end carries a tiller unit 20 including the controls for the motor 2, not specifically illustrated and conventional.
  • the motor 2 is energized by a storage battery 21.
  • the motor 2 is partly enclosed in a casing 1 of tapering, generally circular cross section.
  • the motor axially projects from the open, wider end of the passage in the casing 1, and the narrow end of the casing passage is partly obstructed by seven baffle plates 6 whose narrow edges radiate equiangularly from the axis of the passage through the casing 1.
  • the passage is much longer than wide, and sealed in a radial direction over most of its length.
  • the motor 2 has a torpedo-shaped housing 7 whose front portion 7a has the approximate shape of a cone with rounded apex.
  • a substantially cylindrical middle portion 7b is integral with the front portion 7a and secured to a rear portion 7c which tapers approximately hemispherically to a cylindrical, coaxial bushing 8 from which the output shaft 9 of the motor projects.
  • the shaft carries a propelling screw 10 having two blades. Respective axial parts of three ribs 11 on the housing portions 7b, 7c are fastened to each other by means of screws obscured in the view of FIG. 2 and accessible from the rear through recesses 22 in the rib parts on the housing portion 7c.
  • a vane 13 radially projects from the housing portion 7b opposite the flange 12 which fastens the rod 3 to the housing 7. The free axial edge of the vane 13 is normally attached to the casing 1 as is shown in FIG. 4.
  • the casing 1 is shown in more detail in FIG. 3. It consists of sheet material of uniform thickness and has a front end section 1a which is bell-shaped like the corresponding part of a trumpet and tapers to a first cylindrical section 1b.
  • a conical casing section 1c tapers from the first cylindrical section 1b in a rearward direction to a long second cylindrical section 1d of smaller diameter than the section 1b which bounds the rear orifice of the casing.
  • the motor 2 projects forwardly from the flaring orifice bounded by the front end section 1a, and the supporting rod 3 passes through a slot 14 extending inward from the casing orifice into the first cylindrical section 1b.
  • a major part of the tapering rear portion 7c of the motor housing 7 is spacedly enveloped by the casing section 1c, and the cylindrical housing part 7b axially extends over most of the first cylindrical casing section 1b.
  • the screw 10 is located in the front orifice of the second cylindrical section 1d.
  • Each baffle plate 6 extends along a plane through the casing axis from the rear orifice of the casing forward beyond the axial center of the second cylindrical section 1d.
  • the front end 6' of each plate 6 is located closely adjacent the screw 10 and is bent obliquely in a direction opposite to the direction of screw rotation.
  • the diameters of the several casing sections are selected in such a manner that the effective flow section of the annular space in the first cylindrical casing section 1b is closely similar to or identical with the effective flow section of the second cylindrical casing section 1d behind the screw 10.
  • the screw is axially centered between the orifices of the casing for best pusher action and for its protection.
  • An odd number of baffle plates 6 is combined with the even-numbered blades of the screw 10 because the combination has been found to produce a more uniform propelling force than a combination of even numbers of screw blades with even numbers of baffle plates, or a combination of odd-numbered blades and plates, particularly when the screw is not fully immersed in water.
  • the casing 1 is additionally attached to the motor housing 7 by several brackets 15 of which only one is seen in the drawing.
  • a cable connecting the motor 2 to the battery 21 passes through the hollow interior of the rod 3 to the tiller unit 20, and thence to the battery 21. It has not been shown since it is entirely conventional.
  • the several portions and sections of the housing 7 and of the casing 1, and the baffle plates 6 had the dimensions, in millimeters, listed in the following Table. The measurements refer to external dimensions, but the thickness of the sheet material in the casing 1 is too small to matter.
  • the screw 10 thus was spaced from the two axial orifices of the casing 1 about 80-90 mm.
  • Other dimensions of the preferred propulsion unit may be read from FIGS. 3 and 4 in the light of the dimensions listed in the Table.
  • the effect of the casing 1 on the performance of the propulsion unit was determined in a simplified dynamometer arrangement illustrated in FIG. 5.
  • the rod 3 was suspended from a rail 17 of a fixed frame by means of two clamps 16, 26 connected by a horizontal pivot pin 23.
  • the motor 2 and its screw 10 were immersed to a precise depth in a body of water 24 contained in an elongated, rectangular tank (not shown) in such a manner that the screw 10 was directed longitudinally of the tank.
  • a spring scale 18 was attached by a ring 19 to the fixed frame and by a hook 25 to an eye on the rod 3 approximately as far from the pivot pin 23 as the bottom end of the rod 3.
  • Alternating line current at 220 volts was converted to direct current at 12 volts by a rectifier 27, and an amperemeter 28 indicated the current fed to the motor 2 through the tiller unit 20.
  • the propelling force exerted by the screw 10 was read from the spring scale 18 in arbitrary, but reproducible units.
  • access to the screw 10 is obstructed in a forward direction by the motor housing 7 and in a rearward direction by the baffle plates 6 so that no injuries can be inflicted to a person by the rapidly rotating screw.
  • the circumferential clearance between the plates 6 and the radial clearance between the housing 7 and the casing 1 are too small for accidental or intentional insertion of a human limb, such as the finger of an adult or the arm of a child, to a depth sufficient to reach the screw 10.
  • the safety features of the propulsion unit are available without loss of efficiency and with minimal loss of propelling power by suitably dimensioning the casing 1 and housing 7, the diameters of the middle portion 7b, the first cylindrical casing section 1b, and of the second cylindrical casing section 1d being related approximately as 9 : 14 : 12. It has further been found beneficial to make the diameter ratio of the front orifice of the casing 1 to the first cylindrical casing section 1b approximately 17.5 to 14, and to make the length ratio of the four casing sections 1a, 1b, 1c, 1d 2 : 3.5 : 3.5 : 13.
  • the axial length of the baffle plates 6 should be related to the corresponding dimension of the second cylindrical casing section 1d as 9 : 13.
  • the dimensions listed in the Table satisfy these optimum relationships, but it has been found that they are to be maintained for equally favorable results when the propulsion unit is scaled up or reduced in size.
  • Plastics constitute the illustrated casing 1, housing 7, and baffle plates 6, but other materials of construction may be chosen according to their corrosion resistance and other necessary properties.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Transmission Devices (AREA)
  • Motor Or Generator Frames (AREA)
  • Prevention Of Electric Corrosion (AREA)
US05/793,305 1976-05-11 1977-05-03 Marine propulsion unit with protected screw Expired - Lifetime US4106425A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2620770 1976-05-11
DE2620770A DE2620770C3 (de) 1976-05-11 1976-05-11 Berührungsschutz für die von einem Motor angetriebene Schraube eines Boots

Publications (1)

Publication Number Publication Date
US4106425A true US4106425A (en) 1978-08-15

Family

ID=5977630

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/793,305 Expired - Lifetime US4106425A (en) 1976-05-11 1977-05-03 Marine propulsion unit with protected screw

Country Status (5)

Country Link
US (1) US4106425A (enExample)
JP (1) JPS52137893A (enExample)
DE (1) DE2620770C3 (enExample)
FR (1) FR2351004A1 (enExample)
IT (1) IT1082812B (enExample)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4427393A (en) 1980-10-24 1984-01-24 Vickers Public Limited Company Propulsion of ships
US4666411A (en) * 1984-08-07 1987-05-19 Richard Silvester Thrust augmenter
US4699597A (en) * 1986-04-29 1987-10-13 Oja Ray V Pump attachment for outboard motors
US5009620A (en) * 1990-05-24 1991-04-23 Feranda Sr Louis Propeller guard
US5906522A (en) * 1998-04-01 1999-05-25 Hooper; Robert P. Thrust enhancer for marine propeller
US6676460B1 (en) 2001-07-05 2004-01-13 Maruta Electric Boatworks Llc Electronic propeller guard
US20040090195A1 (en) * 2001-06-11 2004-05-13 Motsenbocker Marvin A. Efficient control, monitoring and energy devices for vehicles such as watercraft
US20050245146A1 (en) * 2003-07-22 2005-11-03 Norman George I System and apparatus for improving safety and thrust from a hydro-drive device
US20060166570A1 (en) * 2004-07-22 2006-07-27 Norman George I System and apparatus for improving safety and thrust from a hydro-drive device
US20060166571A1 (en) * 2005-01-24 2006-07-27 Norman George I Shroud for a hydro thrust device
US7335071B1 (en) 2001-07-05 2008-02-26 Maruta Electric Boatworks Llc Electronic shut off systems
US7465201B1 (en) 2004-09-20 2008-12-16 The United States Of America As Represented By The Secretary Of The Navy Articulation mechanism and elastomeric nozzle for thrust-vectored control of an undersea vehicle
US10399653B1 (en) 2017-09-21 2019-09-03 Craig Silta Jet ski impeller

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0439120Y2 (enExample) * 1985-04-30 1992-09-11
JP3096685B2 (ja) 1999-03-05 2000-10-10 照明 伊藤 試験管ホルダー
DE102015207065A1 (de) * 2015-04-17 2016-10-20 Harro Zufall Vorrichtung zur Anbringung eines Antriebsmittels an einem Standup-Paddle-Board

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2473603A (en) * 1946-01-15 1949-06-21 Josef H Miller Marine propeller device
US2714800A (en) * 1950-10-28 1955-08-09 Aerojet General Co Gasoline air-hydropulse
US2983246A (en) * 1960-08-04 1961-05-09 Manley Audre Marie Propeller guard for outboard motorboat
US3358635A (en) * 1966-05-09 1967-12-19 Clarence E Mcree Swimmer's towing device
DE1269000B (de) * 1966-10-20 1968-05-22 Porsche Kg Schraubenantrieb fuer Boote
US3389558A (en) * 1966-12-15 1968-06-25 Hall Marine Corp Jet propulsion apparatus
US3802377A (en) * 1973-05-24 1974-04-09 S Porter Lower unit weed guard
DE2445324A1 (de) * 1974-07-04 1976-01-22 Egra Anstalt Vorrichtung zur fortbewegung einer person im wasser

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2473603A (en) * 1946-01-15 1949-06-21 Josef H Miller Marine propeller device
US2714800A (en) * 1950-10-28 1955-08-09 Aerojet General Co Gasoline air-hydropulse
US2983246A (en) * 1960-08-04 1961-05-09 Manley Audre Marie Propeller guard for outboard motorboat
US3358635A (en) * 1966-05-09 1967-12-19 Clarence E Mcree Swimmer's towing device
DE1269000B (de) * 1966-10-20 1968-05-22 Porsche Kg Schraubenantrieb fuer Boote
US3389558A (en) * 1966-12-15 1968-06-25 Hall Marine Corp Jet propulsion apparatus
US3802377A (en) * 1973-05-24 1974-04-09 S Porter Lower unit weed guard
DE2445324A1 (de) * 1974-07-04 1976-01-22 Egra Anstalt Vorrichtung zur fortbewegung einer person im wasser

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4427393A (en) 1980-10-24 1984-01-24 Vickers Public Limited Company Propulsion of ships
US4666411A (en) * 1984-08-07 1987-05-19 Richard Silvester Thrust augmenter
US4699597A (en) * 1986-04-29 1987-10-13 Oja Ray V Pump attachment for outboard motors
US5009620A (en) * 1990-05-24 1991-04-23 Feranda Sr Louis Propeller guard
US5906522A (en) * 1998-04-01 1999-05-25 Hooper; Robert P. Thrust enhancer for marine propeller
US20040090195A1 (en) * 2001-06-11 2004-05-13 Motsenbocker Marvin A. Efficient control, monitoring and energy devices for vehicles such as watercraft
US6676460B1 (en) 2001-07-05 2004-01-13 Maruta Electric Boatworks Llc Electronic propeller guard
US7335071B1 (en) 2001-07-05 2008-02-26 Maruta Electric Boatworks Llc Electronic shut off systems
US6986689B2 (en) 2003-07-22 2006-01-17 Enviropropcorporation System and apparatus for improving safety and thrust from a hydro-drive device
US20050245146A1 (en) * 2003-07-22 2005-11-03 Norman George I System and apparatus for improving safety and thrust from a hydro-drive device
US20060166570A1 (en) * 2004-07-22 2006-07-27 Norman George I System and apparatus for improving safety and thrust from a hydro-drive device
US7267589B2 (en) 2004-07-22 2007-09-11 Enviroprop Corporation System and apparatus for improving safety and thrust from a hydro-drive device
US7465201B1 (en) 2004-09-20 2008-12-16 The United States Of America As Represented By The Secretary Of The Navy Articulation mechanism and elastomeric nozzle for thrust-vectored control of an undersea vehicle
US20060166571A1 (en) * 2005-01-24 2006-07-27 Norman George I Shroud for a hydro thrust device
US7229331B2 (en) 2005-01-24 2007-06-12 Enviroprop Corporation Shroud for a hydro thrust device
US10399653B1 (en) 2017-09-21 2019-09-03 Craig Silta Jet ski impeller

Also Published As

Publication number Publication date
JPS52137893A (en) 1977-11-17
FR2351004B1 (enExample) 1980-09-19
IT1082812B (it) 1985-05-21
FR2351004A1 (fr) 1977-12-09
DE2620770A1 (de) 1977-11-17
DE2620770C3 (de) 1979-06-21
DE2620770B2 (de) 1978-10-19

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